MathGroup Archive 1993

[Date Index] [Thread Index] [Author Index]

Search the Archive

Speed When Accessing List Elements Sucks

  • To: mathgroup at
  • Subject: Speed When Accessing List Elements Sucks
  • From: "Michael S. Turok" <turok at>
  • Date: Wed, 5 May 1993 02:47:51 -0400


I have a list and I am trying to calculate the difference between
adjacent elements of the list:

	diff[[n]] = list[[n+1]] - list[[n]]

But it is taking forever!!  The list is about 100 elements long, and I
want to loop this about 50 times.  So, I am trying to create a diff 
matrix that is 50x100.  But, after 30 min. CPU time, only about 20
elements of the first row had been filled in!!!!

I tracked down the problem to the calculation of these differences,
and the real problem seems to be accessing of the elements themselves.
Can anyone please, please, please, help me, before I have to dump this
into C?


  • Prev by Date: AVS
  • Next by Date: Re: Mathematica -> LaTeX
  • Previous by thread: AVS
  • Next by thread: Re: More on i/o and shell commands